JPS6115283B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a servo valve for controlling high-pressure fluid.
In particular, the present invention relates to a servo valve suitable for controlling fluids at extremely high pressures, such as 300 atmospheres to 3000 atmospheres, or low viscosity fluids.

[Conventional technology]

These servo valves are used to control the plate thickness of rolling mills, the acceleration of shakers, and the position and speed of moving objects, but in recent years there has been an increasing demand for high output and high speed. , the hydraulic pressure of the fluid to be controlled is also becoming higher and higher.

A servo valve generally has a structure that combines a pilot valve that controls the supply of low-pressure oil and at least one main valve that can control the supply of high-pressure oil. It is designed to adjust the opening degree of the main valve.

In addition, the main valve is usually provided with two independently operating control ports, and by operating these control ports alternately with a pilot valve, the supply flow rate or pressure of high-pressure oil can be controlled accurately and quickly. It's getting old.

This servo valve will be further explained with reference to FIG.

In FIG. 4, only the main valve of the servo valve is shown, with the pilot valve omitted. This main valve 100 has a spool sliding type valve structure, and the sleeve 10
1, a spouse 102 is slidably fitted therein. The pilot valve (not shown) is a low pressure oil source Ps ₁
hydraulic pressure is supplied to port C ₁ or C ₂ of the valve. Pressure chambers 103 and 104 of the main valve 100 are connected to ports C ₁ and C ₂ of the pilot valve, respectively, and the spool 102 of the main valve 100 is actuated alternately on the left and right sides in the figure by hydraulic pressure from the pilot valve.

The spool 102 is connected to the pressure chamber 10 as shown in the figure.
3 and 104, and valve parts 107, 108, and 109 are integrally provided, and a sliding valve seat 110 provided on the sleeve 101. ，
112 and 113 and valve portions 107, 108 and 109 have a structure in which valve action is performed.

As shown, the sleeve 101 is provided with a drain port T, a port connected to the high pressure oil source Ps ₂ , and ports C ₃ and C ₄ . In the main valve 100, when the spool 102 is moved to the left in the figure, the drain port T and the port _C3 are connected to each other, and when the spool 102 is moved to the right in the figure, the high pressure oil source Ps ₂ port is connected to the drain port T. _C4
When the spool 102 is placed in the center position, there is no communication between any of the ports.

The operation of such a conventional servo valve will be explained.

If the pressures at ports C ₁ and C ₂ of the pilot valve are the same, this is the so-called central position, and the main valve 10
Both valve portions 107 and 108 of No. 0 are in a sealed state.

Therefore, the pilot spool 16 is driven to connect the port C ₁ to the hydraulic power source Ps ₁ , and the port
When _C2 is communicated with a drain port (not shown), control hydraulic pressure is supplied to the pressure chamber 103 on the left side of the main valve 100, and the left piston section 105 receives pressure and moves the spool 102 to the right. , high pressure oil is supplied from Ps ₂ through port C ₄ . In this case, the left valve portion 107 is in a closed state.

Conversely, connect port _C2 of the pilot valve to a low pressure hydraulic source.
Ps ₁ and port C ₁ are connected to the drain port, pressure chamber 1 on the left side of main valve 100
04 is supplied with control hydraulic pressure to move the spool 102 to the left, port _C3 is communicated with drain port _T3 , and the high hydraulic pressure of the load is released.

[Problem that the invention seeks to solve]

This kind of spool sliding type servo valve is 200
Although it can be used with little leakage at pressures up to about atmospheric pressure, when the pressure exceeds 350 atmospheres, leakage becomes large even in the case of mineral oil-based fluids due to the gap between the spool 102 and the sleeve 101. For aqueous fluids, etc., the leakage rate becomes extremely large and the durability deteriorates, making it practically unusable. In particular, since the amount of leakage is proportional to the pressure and the gap between the spool 102 and the sleeve 101, there is a problem that the higher the pressure, the more the amount of leakage increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a servo valve that can control the flow rate or pressure of fluid precisely and at high speed, with sufficient durability and reliability, and with little leakage even at ultra-high pressures of 500 atmospheres or more.

[Means for solving problems]

The present invention, which solves the above problems, provides a servo valve comprising a pilot valve that controls the supply of low oil pressure and a main valve that is driven by the oil pressure supplied from the pilot valve and controls the supply of high oil pressure. The main valve is provided with two high oil pressure control ports in the housing, and each high oil pressure control port is configured with a poppet valve, and the valve bodies of the two poppet valves are elastically connected via an elastic member. The present invention is characterized in that a position detector is provided for connecting the poppet valve and detecting the position of the valve body of the poppet valve from the displacement of the elastic member.

[Effect]

In the neutral position, the valve body of the poppet valve is pressed against the poppet surface within the housing by the elastic force of the elastic member. Here, when one poppet valve is opened by hydraulic pressure from the pilot valve, the valve body of the other poppet valve is pressed even more strongly against the poppet surface via the elastic member. This will eliminate leakage from the poppet valve.

Further, since the position of the valve body of the poppet valve can be detected by the position detector, the opening degree of the valve body can be adjusted to a desired value. This makes it possible to precisely adjust the flow rate or pressure of the fluid.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the pilot valve 12 has a spool sliding type valve structure, and the pilot sleeve 1
A pilot spool 16 is slidably fitted into the spool 4. The pilot spool 16 is driven axially by a drive 18. The drive section 18
includes a magnet 20, a force motor 22 disposed within the magnet and connected to the pilot spool 16, an electromagnetic coil 24 wound around the outer circumference of the force motor 22, and the force motor 22.
It is composed of springs 26 and 28 for regulating the initial position (neutral position) of the. Reference numeral 30 indicates a screw member for adjusting the neutral position.

The pilot spool 16 in FIG. 1 is a four-way valve that supplies hydraulic pressure from a low-pressure oil source Ps ₁ to port C ₁ or C ₂ . That is, when current is applied to the electromagnetic coil 24 to drive the force motor 22 to the left in the drawing, low oil pressure Ps ₁ is supplied to port C ₁ and at the same time port C ₂ becomes a drain port.
Connected to _T2 . On the other hand, when the force motor 22 is driven to the right, the low oil pressure Ps ₁ is supplied to the port C ₂ and at the same time, the port C ₁ is communicated with the drain port T ₁ .

Ports C ₁ and C ₂ of pilot valve 12 are connected to pressure chambers 34 and 36, respectively, of main valve 32, and hydraulic pressure from pilot valve 12 alternately operates main spools 38 and 40 of main valve 32.

A large diameter pressure receiving piston 4 is located in the pressure chambers 34 and 36 of each main spool 38 and 40.
2 and 44 are slidably disposed. Further, each of the main spools 38 and 40 has a poppet valve 52 and 54, respectively, facing a sealing surface (poppet surface) 48 and 50 formed on the periphery of the end surface of the hole provided in the housing 46 of the main valve 32. It is formed. Two control ports of the main valve 32 are defined by the sealing surfaces 48 or 50 and the poppet valve body 52 or 54.

The two main spools 38 and 40 are elastically connected to each other via an elastic member 56. This elastic member 56 consists of three plates 58, 60, and 62, and rubber-like elastic bodies 64, 6 fixed by baking or the like between each plate 58, 60, 62.
It consists of 6. right side plate 62
is fixed to the right main spool 40. A left rod 68 passing through the center hole of the left main spool 38 is fixed to the left plate 58, and a nut 70 is screwed into the left end of the rod and hooked to the left end surface of the main spool.

On the other hand, a right rod 72 extending to the right is fixed to the center plate 60, and the right rod 72 is connected to the right elastic body 66 and the right plate 60.
It passes through a center hole formed in the left main spool 40 and projects to the right side of the main spool 40. A position detection rod portion 72A is formed at the right end of the right rod 72, and together with an induction coil 74 provided in the housing 46, constitutes a position detector. That is, the position detector can detect the position from the displacement of the elastic member 56.

A high pressure oil source Ss ₂ is connected to one port of the main valve 32 . The main valve 32 supplies high pressure oil to the sealing surface 4
8, 50 and poppet valve bodies 52, 54. In addition, the main valve 32 has a high pressure port.
C ₃ and C ₄ are provided, and high pressure ports C ₃ and C ₄ are connected to a working load such as a ram of a rolling mill.
Note that C ₃ and C ₄ are high pressure ports, and T ₃ is the drain port of the main valve.

By tightening a nut 70 threaded onto the left side of the left rod 68, each poppet valve body 52, 54 is brought into contact with its respective sealing surface 48, 50 with the same predetermined pressing force on both sides. In this case, since the rubber-like elastic bodies 64 and 66 undergo tensile deformation, the pressing force against each poppet valve body 52 and 54 is generated by the elastic force of these elastic bodies. The center plate 60 is provided at a position where it moves a distance equal to 1/2 of the combined deflection of the left and right elastic bodies 64, 66. That is, the left and right elastic bodies 64 and 66 are arranged so that the axial deflections thereof are the same. Therefore, by using the position detectors 72A and 74 that detect the movement of the right rod 72 connected to the center plate 60, it is possible to correctly detect a change in the position of the left or right main spool with a gain of 1/2. can.

The servo valve of the present invention has the configuration described above, and its operation will now be described.

When the pressures at ports C ₁ and C ₂ of the pilot valve are the same, this is the so-called neutral position, and the main valve 32
Both poppet valves are in a sealed state.

Therefore, the pilot spool 16 is driven to the left to connect the port _C1 to the hydraulic power source _Ps1 , and
When port C ₂ is connected to drain port T ₂ ,
Control hydraulic pressure is supplied to the pressure chamber 34 on the left side of the main valve,
The left poppet valve body 52 is moved to the left by the displacement of the elastic bodies 64, 66, and high pressure oil is supplied from _Ps2 through _C3 . In this case, the poppet valve body 54 on the right side is strongly pressed against the sealing surface 50 and becomes completely sealed.

Conversely, when the port C ₂ is communicated with the hydraulic power source Ps ₁ and the port C ₁ is communicated with the drain port T ₁ , the poppet valve body 54 on the right side is moved to the right.
In addition, the elastic bodies 64 and 66 are displaced, and the port _C4 is communicated with the drain port _T3 , thereby releasing the high hydraulic pressure of the load. In this case, the left poppet valve body 52
The sealing surface 4 is compressed by the elastic force of the elastic bodies 64 and 66.
8 and is strongly pressed to create a complete seal.

That is, two poppet valves 48, 52, 5
0 and 54 operate as an integrated three-way valve with a slight dead band due to the initial pressing force of the elastic bodies 64 and 66. Since the control port of the main valve 32 is constructed with this poppet valve, oil leakage can be kept extremely small, making it ideal for use when Ps ₂ is an ultra-high pressure (500 atmospheres or more) or for aqueous low-viscosity fluids. However, a servo valve with less leakage can be obtained. moreover,
Since the poppet valve is insensitive to wear caused by foreign matter in the liquid, a servo valve with excellent durability and reliability can be obtained.

In order to control the opening degree of the main spools 38, 40 of the main valve 32 proportionally to the command signal, it is necessary to detect the displacement of the valve bodies 52, 54 of each poppet valve and feed back the displacement. be. FIG. 2 is a diagram showing a position servo device (system) for implementing this proportional control.

In FIG. 2, the symbol X indicates a command signal to the drive section of the pilot valve 18, and indicates the current value supplied to the electromagnetic coil 24 of the force motor 22 in FIG. This command signal is corrected by a displacement signal Y fed back from position detectors 72A, 74 that detect the displacement position (control port opening degree) of the poppet valve bodies 52, 54 of the main valve 32. In this way, the opening degree of the control port of the main valve 32 to be controlled can be proportionally controlled while being constantly fed back to the command signal.

The servo valve of the present invention as shown in FIG. 1 is suitable for use in the position servo device shown in FIG. For example, if two position detectors that individually detect the displacement of each poppet valve are provided in place of the elastic member 56 and one position detector 72A, 74 in FIG. 1, each detector will suffer from drift. and adders are needed, etc.
It will be very difficult to implement. However, in the servo valve of the present invention, the central plate 60 is provided at a position where the deflection of the elastic member 56 is halved, and the structure is such that the positions of the two left and right poppet valves can be detected using this single plate. It becomes very easy to construct a position servo device (see FIG. 2) for control. In this case, the center plate 60 will move by 1/2 of the leftward movement of the left poppet valve body 52 and 1/2 of the rightward movement of the right poppet valve body 54, These movements will be detected with a gain of 1/2.

Furthermore, according to this embodiment, the two left and right main spools 38 and 40 can be separated into the left and right parts by simply loosening the nut 70 that is engaged with the screw of the left rod 68. Assembly becomes easy. Further, according to this embodiment, by simply adjusting the nut 70, the seat surfaces 48 of the valve bodies 52, 54,
50 can be easily and accurately adjusted.

FIG. 3 is a diagram showing another embodiment in which the servo valve shown in FIG. 1 is partially modified.

In FIG. 3, pressure receiving pistons 42 and 44 of left and right main spools 38 and 40 are shown.
Pressure chambers 82 and 84 are also provided outside the left side pressure chamber 82 and port C ₂ from the pilot valve.
A branch oil passage 86 communicating with the pressure chamber 8 on the right side
A branch oil passage 88 is added that communicates between the pilot valve 4 and the port _C1 from the pilot valve. The rest is substantially the same as the embodiment shown in FIG. According to the structure shown in FIG. 3, pressure oil can be supplied to both the left and right sides of each pressure receiving piston, so that the control operation of the main valve can be further facilitated. That is, when displacing the left main spool 38 to the left, the hydraulic pressure from port C ₁ acts on the right side of the left pressure receiving piston 42 and at the same time acts on the right side of the right pressure receiving piston 44 to assist them. Both actuation forces can be utilized. In this way, by increasing the hydraulic actuation force to the main spool, the elastic member 5
6 can be reduced, and therefore the contact force between the poppet valve body and the sealing surface can be reduced.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, the two control ports of the main valve are configured with poppet valves, and each valve body is connected with an elastic member, so even in the case of ultra-high pressure fluid, there is no leakage. Accordingly, it is possible to obtain a servo valve and a position servo device that can accurately control pressure or flow rate with less pressure or flow rate. Further, according to the present invention, the valve bodies of the left and right poppet valves are connected via the elastic body, and the valve bodies are pressed against the respective seat surfaces by the elastic force of the elastic body, so that the valve bodies of the left and right poppet valves are pressed against the respective seat surfaces. Another advantage is that the pressing force is the same on the left and right sides.

Furthermore, according to the present invention, the displacement of the left and right poppet valves can be detected from the displacement of the elastic member, so position detection for proportional control is as easy as with ordinary spool sliding type valves. and its control can be done just as easily.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the servo valve of the present invention, FIG. 2 is an explanatory diagram showing the arrangement of a position servo device using the servo valve of the present invention, and FIG. 3 is a sectional view showing an embodiment of the servo valve of the present invention. FIG. 4 is a sectional view showing a conventional servo valve. 12...Pilot valve, 14...Pilot sleeve, 16...Pilot spool, 18...
Drive unit, 22...Force motor, 32...Main valve, 34, 36...Pressure chamber, 38, 40...Main spool, 46...Main valve housing, 48, 50
... Seal surface, 52, 54 ... Poppet valve body, 5
6...Elastic member, 64, 66...Elastic body, 74...
...Position detector.

Claims (1)

[Scope of Claims] 1. A pilot valve that controls the supply of low oil pressure, and a pilot valve that is driven by the oil pressure supplied from the pilot valve,
A servo valve comprising a main valve for controlling the supply of high oil pressure, wherein the main valve is provided with two high oil pressure control ports in the housing, and each high oil pressure control port is configured with a poppet valve, The valve bodies of the two poppet valves are elastically connected via an elastic member, and a position detector is provided for detecting the position of the valve body of each poppet valve from the displacement of the elastic member. Characteristic servo valve. 2. The servo valve according to claim 1, wherein the position detector is capable of detecting displacement of each poppet valve at a position where the deflection of the elastic member is halved.